Abstract

In finding all solutions to a constraint satisfactionproblem, or proving that there are none, with asearch algorithm that backtracks chronologicallyand forms k-way branches, the order in which thevalues are assigned is immaterial. However, weshow that if the values of a variable are assignedinstead via a sequence of binary choice points, andthe removal of the value just tried from the domainof the variable is propagated before another valueis selected, the value ordering can affect the searcheffort. We show that this depends on the problemconstraints; for some types of constraints, we showthat the savings in search effort can be significant,given a good value ordering